Emergency downgraded at Wanapum Dam

Originally published March 5, 2014 at 7:41 pm
Updated March 5, 2014 at 11:26 pm

The crack in a spillway pier at the Wanapum Dam has been downgraded to a "non-failure emergency," meaning the pier is no longer considered at risk of collapsing, the Grant County Public Utility District said Wednesday.

The crack in a spillway pier at the Wanapum Dam has been downgraded to a “non-failure emergency,” meaning the pier is no longer considered at risk of collapsing, the Grant County Public Utility District said Wednesday.

The downgrade is the result of engineering surveys Monday and Tuesday that show the fractured area found on one of the dam’s spillways was continuing to stabilize, the PUD said in a news release.

“This is still a serious issue,” said Chuck Allen, a public affairs officer for the PUD.

As of 6 p.m. Tuesday, surveys showed that the impacted area was stable, the PUD said.

The crack has closed and a section of the spillway pier that had shifted has nearly returned to full alignment, the PUD said. That’s the result of the utility lowering the water level by 26 feet in the reservoir behind the dam, reducing pressure on the damaged spillway, the PUD said.

The 65-foot-long crack was discovered Feb. 27, and the dam had operated under the status of a “developing failure,” since Friday, the PUD said.

Officials were still trying to determine what caused the crack and have not developed a plan for repairing the damage, Allen said.

The reservoir level will remain at 26 feet below normal for the foreseeable future, Allen said.

As a result, the dam is generating electricity at about half of its total capacity of 700 megawatts, he said. But it continues to meet customer electricity demands at the reduced level, the PUD said.

The 2-inch-wide underwater crack extends horizontally across the upstream side of the 65-foot-wide pier. It’s one of 12 piers on the spillway.

A spillway is the portion of the dam that allows water to “spill” past the dam as opposed to running through the turbines.

The reduced water level behind the dam means that all boat launches on the Priest Rapids and Wanapum reservoirs remain closed. The Wanapum Heritage Center and the day-use park at Wanapum Dam are also closed, the PUD said.

Lowering the reservoir has exposed shoreline that had been covered with water since the dam filled 50 years ago, said Grant County PUD spokesman Tom Stredwick.

“It’s an opportunity to see something you wouldn’t normally see,” he said Tuesday.

Visitors were snapping photographs of the area Tuesday, while others walked amid the rocks and sandbars, the Yakima Herald-Republic reported. A family was exploring with a metal detector.

The banks of the Columbia are a rich source of tribal artifacts since Indians lived along the river and used it for travel for generations, said Allyson Brooks, the Washington state historic preservation officer.

She is concerned about looters digging into sites that were inundated, or amateur archaeologists looking for items such as stone tools.

“If they impacted a burial area, it would be a felony,” Brooks said Tuesday in Olympia.

The Washington state physical anthropologist will take a look at bones found Tuesday along the Columbia in an area uncovered by the reservoir drawdown.

Grant County Coroner Craig Morrison said Wednesday he’s turning the case over to the state Department of Archaeology and Historic Preservation after determining the bones were very old.

Anthropologist Guy Tasa said he’ll first determine whether the bones are Native American. If so, he’ll contact area tribes about disposing of them. If not, he’ll work with the Grant County PUD to come up with a solution for the remains.